The invention relates to the use of deltorphins to attenuate or prevent cytokine mediated hepatic injury.
Hepatic injury can be caused by a number of different agents including viruses such as Hepatitis A, B, C, D and E, both gram positive and gram negative bacteria, chemical agents such as ethanol, carbon tetrachloride and lead, and by physical trauma resulting in ischemia (ischemic hepatitis) injuries as can occur in right-sided congestive heart failure. It is now believed that all of these types of hepatic injury are caused at least in part by the liver""s inflammatory or cytokine response to these agents. The inflammatory response of the liver results in the overexpression of a cascade of inflammatory/acute phase cytokines, such as interleukin-1 (IL-1), tumor necrosis factor (TNF), IL-6, IL-8 and transforming growth factor beta (TGFxcex2). It is now believed that it is the cascade of these cytokines which is the ultimate cause of much of the hepatic injury resulting from these agents. Thus, there is a need for a therapeutic agent which can be useful in alleviating or modulating the inflammatory response associated with liver disease or injury.
The present invention fills this need by providing a method of treating or preventing a cytokine mediated hepatic injury in a mammal comprised of administering a pharmaceutically effective amount of a deltorphin to said mammal. The hepatic injury can be an acute inflammatory reaction, as a result of a viral or bacterial infection or a chemical agent such as ethanol, lead, carbon tetrachloride or acetaminophen, or from trauma resulting in ischemia or reperfusion injury in the liver.
The present invention is also directed to a method of treating a viral or bacterial infection-related hepatic damage in a mammal comprised of administering a pharmaceutically effective amount of a deltorphin to said mammal.
The present invention is also directed to a method of treating alcohol induced liver injury in a mammal comprised of administering a pharmaceutically effective amount of a deltorphin to said mammal.
Preferably, the deltorphin is administered in a pharmaceutical composition at a dosage of from about 0.5 mg/kg to about 20 mg/kg, or alternatively lower doses from about 1 xcexcg/kg to about 1000 xcexcg/kg of deltorphin per body weight of the mammal.
Preferably, the mammal is a human.
Deltorphins are endogenous linear heptapeptides isolated from skin extracts of the South American frog Phyllomedusa bicolor. These may be further divided into deltorphin I SEQ ID NO:1 and deltorphin II SEQ ID NO:2 depending on their amino acid sequence. Deltorphin I SEQ ID NO:1 has the amino acid sequence Tyr-Ala-Phe-Asp-Val-Val-Gly-NH2 with alanine as either the D- or L-isomer. Deltorphin II SEQ ID NO:2 has the amino acid sequence Tyr-Ala-Phe-Glu-Val-Val-Gly-NH2 with alanine as either the D- or L-isomer. Either deltorphin I SEQ ID NO:1, deltorphin II SEQ ID NO:2 or a combination of deltorphin I SEQ ID NO:1 and II SEQ ID NO:2 may be used in the invention. Deltorphins may be obtained from frog skin extracts, or they may be purchased from a vendor such as Peninsula Laboratories, Inc. (Belmont, Calif.) or may be synthesized using a peptide synthesizer such the type available from Applied Biosystems.
Deltorphins are administered to a mammal to modulate cytokine activation by blocking one or more steps in the cytokine cascade. Deltorphins may be formulated for administration in an aqueous based liquid such as phosphate buffered saline to form an emulsion, or they may be formulated in an organic liquid such as dimethylsulfoxide to form a solution. The solution or emulsion may be administered by any route, but it is preferably administered parenterally such as by intravenous, intramuscular, intradermal or intraperitoneal injections. A preferred dose is in the range of about 0.5-20 mg, or alternatively lower doses of about 1-1000 xcexcg of deltorphin per kg of body weight of the mammal. The time of administration of the deltorphin is preferably prior to initiation of cytokine activation. However, the deltorphin may be administered concurrently with another agent that induces cytokine activation or even subsequent to an agent that induces cytokine activation and still produce a protective effect.
Deltorphin administration should be continued on a daily basis until hepatic function returns to normal and is maintained at normal levels, preferably for at least one to two days. Hepatic injury can be determined by elevated levels of hepatic enzymes, as well as by depressed albumin levels (less than about 35 g/liter). Hepatic function is routinely monitored by quantitating serum levels of hepatic enzymes such as alanine aminotransferase (ALT) (normal less than 35 U/L), aspartate aminotransferase (AST) (normal less than 30 U/L), alkaline phosphatase (ALP) (normalxe2x89xa6100 U/L) and gamma glutamyltransferase (GGT) (normalxe2x89xa645 U/L for males, xe2x89xa630 U/L for females), as well as bilirubin, both conjugated (normalxe2x89xa60.2 mg/deciliter) and total (normalxe2x89xa61.0 mg/deciliter) bilirubin. Deltorphin modulation of hepatocyte cytokine activation may be used therapeutically in a variety of hepatic injury processes. As used herein, the term hepatic injury broadly encompasses all types of injury such as hepatic trauma, physical and/or chemical insult, stress, inflammation, toxicity, disease and so on. For example, deltorphins can be used in treating hepatic injury due to alcoholic liver disease, acetaminophen toxicity, cadmium toxicity, lead poisoning, bacteremia due to, for example, Staphylococcus species, Streptococcus species, Neisseria species, Salmonella species, Shigella species, Escherichia coli, Clostridium perfringens, Klebsiella species, Proteus species, Enterobacter species, Bacteroides species, Brucella species, Francisella tularensis, Listeria monocytogenes, Acinetobacter species, Streptobacillus moniliformis, Vibrio species, Helicobacter pylori, Pseudomonas species, Haemophilus species, Bordetella pertussis, viral infections due to, for example, influenza viruses, adenoviruses, paramyxoviruses, rubella viruses, polioviruses, hepatitis viruses, herpesviruses, rabies viruses, human immunodeficiency viruses and papilloma viruses, as well as trauma, ischemia reperfusion injury and metabolic liver disease.
While the specific mechanism of deltorphin action on the modulation of cytokine mediated hepatic injury such as acute inflammatory reactions, trauma and toxin induced biological responses is unknown, deltorphins exhibit a specific and reproducible effect on decreasing hepatotoxicity. This invention will be further appreciated in light of the following example.